Method of controlling the operating parameters of a surgical system

ABSTRACT

A control system for a surgical system that includes an irrigation fluid flow sensing capability. The sensing capability may be placed in the control console or in the handpiece. Irrigation flow measurements provided by the sensing capability allows the control system to vary irrigation pressure and/or flow, aspiration pressure and/or flow and power supplied to the handpiece more accurately than prior art sensors that monitor aspiration flow.

BACKGROUND OF THE INVENTION

This invention relates generally to the field of microsurgery and moreparticularly to a control system for an ophthalmic surgery system.

The human eye in its simplest terms functions to provide vision bytransmitting light through a clear outer portion called the cornea, andfocusing the image by way of the lens onto the retina. The quality ofthe focused image depends on many factors including the size and shapeof the eye, and the transparency of the cornea and lens.

When age or disease causes the lens to become less transparent, visiondeteriorates because of the diminished light which can be transmitted tothe retina. This deficiency in the lens of the eye is medically known asa cataract. An accepted treatment for this condition is surgical removalof the lens and replacement of the lens function by an artificialintraocular lens (IOL).

In the United States, the majority of cataractous lenses are removed bya surgical technique called phacoemulsification. During this procedure,a thin phacoemulsification cutting tip is inserted into the diseasedlens and vibrated ultrasonically. The vibrating cutting tip liquifies oremulsifies the lens so that the lens may be aspirated out of the eye.The diseased lens, once removed, is replaced by an artificial lens.

A typical ultrasonic surgical device suitable for ophthalmic proceduresconsists of an ultrasonically driven handpiece, an attached cutting tip,and irrigating sleeve and an electronic control console. The handpieceassembly is attached to the control console by an electric cable andflexible tubings. Through the electric cable, the console varies thepower level transmitted by the handpiece to the attached cutting tip andthe flexible tubings supply irrigation fluid to and draw aspirationfluid from the eye through the handpiece assembly.

The operative part of the handpiece is a centrally located, hollowresonating bar or horn directly attached to a set of piezoelectriccrystals. The crystals supply the required ultrasonic vibration neededto drive both the horn and the attached cutting tip duringphacoemulsification and are controlled by the console. The crystal/hornassembly is suspended within the hollow body or shell of the handpieceby flexible mountings. The handpiece body terminates in a reduceddiameter portion or nosecone at the body's distal end. The nosecone isexternally threaded to accept the irrigation sleeve. Likewise, the hornbore is internally threaded at its distal end to receive the externalthreads of the cutting tip. The irrigation sleeve also has an internallythreaded bore that is screwed onto the external threads of the nosecone.The cutting tip is adjusted so that the tip projects only apredetermined amount past the open end of the irrigating sleeve.Ultrasonic handpieces and cutting tips are more fully described in U.S.Pat. Nos. 3,589,363; 4,223,676; 4,246,902; 4,493,694; 4,515,583;4,589,415; 4,609,368; 4,869,715; 4,922,902; 4,989,583; 5,154,694 and5,359,996, the entire contents of which are incorporated herein byreference.

In use, the ends of the cutting tip and irrigating sleeve are insertedinto a small incision of predetermined width in the cornea, sclera, orother location. The cutting tip is ultrasonically vibrated along itslongitudinal axis within the irrigating sleeve by the crystal-drivenultrasonic horn, thereby emulsifying the selected tissue in situ. Thehollow bore of the cutting tip communicates with the bore in the hornthat in turn communicates with the aspiration line from the handpiece tothe console. A reduced pressure or vacuum source in the console draws oraspirates the emulsified tissue from the eye through the open end of thecutting tip, the cutting tip and horn bores and the aspiration line andinto a collection device. The aspiration of emulsified tissue is aidedby a saline flushing solution or irrigant that is injected into thesurgical site through the small annular gap between the inside surfaceof the irrigating sleeve and the cutting tip.

The preferred surgical technique is to make the incision into theanterior chamber of the eye as small as possible in order to reduce therisk of induced astigmatism. These small incisions result in a verytight wounds that squeeze the irrigating sleeve tightly against thevibrating tip. Friction between the irrigating sleeve and the vibratingtip generates heat, but the risk of the tip overheating and causing aburn to the tissue is reduces by the cooling effect of the aspiratedfluid flowing inside the tip. When the tip becomes occluded with tissue,this aspiration flow can be reduced or eliminated, allowing the tip toheat up.

Prior art devices have used sensors that detect large rises inaspiration vacuum, and predict occlusions based on vacuum rise. Based onthis sensed occlusion, power to the handpiece may be reduced and/orirrigation and aspiration flows can be increased. See U.S. Pat. Nos.5,591,127, 5,700,240 and 5,766,146 (Barwick, Jr., et al.), the entirecontents of which being incorporated herein by reference. Increasedvacuum levels in the aspiration line, however, do not necessarilyindicate that the flow of cooling fluid around the tip has been cut off.Even with the tightest incisions, some irrigating fluid will leak outbetween the wound and the outside of the irrigating sleeve. The woundleakage also provides addition cooling flow to the incision site, andmeasuring rises in aspiration vacuum alone does not necessarily indicatethat a potential for a corneal burn exists. Therefore, power to thehandpiece may be interrupted prematurely.

Therefore, a need continues to exist for a control system for a surgicalhandpiece that utilizes a better indication of fluid flow at the tip forthe control of ultrasonic power levels.

BRIEF SUMMARY OF THE INVENTION

The present invention improves upon the prior art by providing a controlsystem for a surgical system that includes an irrigation fluid flowsensing capability. The sensing capability may be placed in the controlconsole or in the handpiece. Irrigation flow measurements provided bythe sensing capability allows the control system to vary irrigationpressure and/or flow, aspiration pressure and/or flow and power suppliedto the handpiece more accurately than prior art sensors that monitoraspiration flow.

Accordingly, one objective of the present invention is to provide asurgical console control system.

Another objective of the present invention is to provide a surgicalconsole control system having an irrigation flow sensing capability.

Another objective of the present invention is to provide a surgicalconsole control system that provides more accurate control of thehandpiece operating parameters.

Another objective of the present invention is to provide a surgicalconsole control system that provides more accurate control of theinfusion operating parameters.

Another objective of the present invention is to provide a surgicalconsole control system that provides more accurate control of theaspiration operating parameters.

These and other advantages and objectives of the present invention willbecome apparent from the detailed description and claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a first embodiment of a control system thatcan be used with the present invention showing the flow sensor in theinstrument.

FIG. 2 is a block diagram of a second embodiment of a control systemthat can be used with the present invention showing the flow sensor inthe handpiece.

FIG. 3 is a block diagram of a third embodiment of a control system thatcan be used with the present invention showing the flow sensor in theinstrument and pressurized infusion control of the infusion source.

FIG. 4 is a block diagram of a fourth embodiment of a control systemthat can be used with the present invention showing the flow sensor inthe handpiece and pressurized infusion control of the infusion source.

FIG. 5 is a block diagram of a fifth embodiment of a control system thatcan be used with the present invention showing a flow sensor in theinstrument and measuring air flow of the pressurized infusion source tocalculate infusion fluid flow.

FIG. 6 is a block diagram of a sixth embodiment of a control system thatcan be used with the present invention showing the pressurized infusionsource as a compressed compliant bag and the infusion fluid flowcalculated from the rate of infusion source compression.

FIG. 7 is a flow chart illustrating the operation of an infusion flowcontrol mode that can be used with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As seen in FIG. 1, in a first embodiment of the present invention,control system 10 for use in operating handpiece 12 includes controlconsole 14. Control console 14 generally includes control module or CPU16, aspiration pump 18, handpiece power supply 20, irrigation flowsensor 22 and valve 24. Console 14 may be any commercially availablesurgical control console such as the ACCURUS® surgical system availablefrom Alcon Laboratories, Inc., Fort Worth, Tex. CPU 16 may be anysuitable microprocessor, micro controller, computer or digital logiccontroller. Pump 18 may be any suitable pump, such as a peristaltic,diaphragm or venturi pump. Power supply 20 may be any suitableultrasound driver, such as incorporated in the ACCURUS® surgical systemavailable from Alcon Laboratories, Inc., Fort Worth, Tex. Sensor 22 maybe any commercially available flow sensor, such as Models Nos. T101D orT201D available from Transonic Systems, Inc., Ithaca, N.Y. Valve 24 maybe any suitable valve such as a solenoid-activated pinch valve. Infusionsource 26 may be any commercially available irrigation solution providedin bottles or bags.

In use, sensor 22 is connected to handpiece 12 and infusion fluid source26 through irrigation lines 30, 32 and 34. Sensor 22 measures the flowof irrigation fluid from source 26 to handpiece 12 and supplies thisinformation to CPU 16 through cable 36. The irrigation fluid flow datamay be used by CPU 16 to control the operating parameters of console 14using software commands that are well known in the art. For example, CPU16 may, through cable 40, vary the output of power supply 20 being sentto handpiece 12 though power cable 42. CPU 16 may also use data suppliedby sensor 22 to vary the operation of pump 18 through cable 44, whichaspirates fluid from handpiece 12 through line 46 and into collectioncontainer 28 through line 48. CPU 16 may also use data supplied bysensor 22 and the applied output of power supply 20 to provide audibletones to the user.

As seen in FIG. 2, in a second embodiment of the present invention,control system 110 for use in operating handpiece 112 includes controlconsole 114. Control console 114 generally includes control module orCPU 116, aspiration pump 118, handpiece power supply 120 and valve 124.Flow sensor 122 is contained within handpiece 112.

In use, tip 150 is connected to fluid source 126 through sensor 122through irrigation lines 130, 132 and 134. Sensor 122 measures the flowof irrigation fluid from source 126 to tip 150 and supplies thisinformation to CPU 116 through cable 136. CPU 116, through cable 138,may open and close valve 124 so as to vary the amount of irrigationfluid reaching tip 150 from source 126. CPU 116 may also, through cable140, vary the output of power supply 120 being sent to handpiece 112through power cable 142. CPU 116 may also use data supplied by sensor122 to vary the operation of pump 118 through cable 144, which aspiratesfluid from handpiece 112 through line 146 and into collection container128 through line 148. CPU 116 may also use data supplied by sensor 122and the applied output of power supply 120 to provide audible tones tothe user.

As seen in FIG. 3, in a third embodiment of the present invention,control system 210 for use in operating handpiece 212 includes controlconsole 214. Control console 214 generally includes control module orCPU 216, aspiration pump 218, handpiece power supply 220, valve 224,pressurizing source 229, and pressure sensor 227. Flow sensor 222 isconnected to handpiece 212 and infusion fluid source 226 throughirrigation lines 230, 232 and 234. Infusion source 226 may be anycommercially available irrigation solution provided in bottles.Pressurizing source 229 pressurizes infusion source 226 through line 252and is controlled by CPU 216 through cable 250. Pressurizing source 229may be any commercially available pressure controller, such asincorporated in the ACCURUS® surgical system available from AlconLaboratories, Inc., Fort Worth, Tex. Pressure sensor 227 measures thepressure of infusion source 226 through lines 254 and is monitored byCPU 216 through cable 256. Pressure sensor 227 may be any suitablecommercially available pressure sensor, such as Model MPX5100 availablefrom Motorola, Inc., Phoenix, Ariz.

In use, sensor 222 measures the flow of irrigation fluid from source 226to handpiece 212 and supplies this information to CPU 216 through cable236. The irrigation fluid flow data may be used by CPU 216 to controlthe operating parameters of console 214 using software commands that arewell known in the art. For example, CPU 216, through cable 250, maycontrol pressurizing source 229 while reading pressure sensor 227 datathrough cable 256 so as to vary the pressure and amount of irrigationfluid reaching handpiece 212 from source 226. CPU 216 may also, throughcable 240, vary the output of power supply 220 being sent to handpiece212 through power cable 242. CPU 216 may also use data supplied bysensor 222 to vary the operation of pump 218 through line 244, whichaspirates fluid from handpiece 212 through line 246 and into collectioncontainer 228 through line 248. CPU 216 may also use data supplied bysensor 222 and the applied output of power supply 220 to provide audibletones to the user.

As seen in FIG. 4, in a fourth embodiment of the present invention,control system 310 for use in operating handpiece 312 includes controlconsole 314. Control console 314 generally includes control module orCPU 316, aspiration pump 318, handpiece power supply 320, valve 324,pressurizing source 329, and pressure sensor 327. Flow sensor 322 iscontained within handpiece 312. Infusion source 326 may be anycommercially available irrigation solution provided in bottles.Pressurizing source 329 may be any commercially available pressurecontroller. Pressure sensor 327 may be any suitable commerciallyavailable pressure sensor.

In use, sensor 322 measures the flow of irrigation fluid from source 326to handpiece 312 and supplies this information to CPU 316 through cable336. The irrigation fluid flow data may be used by CPU 316 to controlthe operating parameters of console 314 using software commands that arewell known in the art. For example, CPU 316, through cable 350, maycontrol pressurizing source 329 while reading pressure sensor 327 datathrough cable 356 so as to vary the pressure and amount of irrigationfluid reaching handpiece 312 from source 326. CPU 316 may also, throughcable 340, vary the output of power supply 320 being sent to handpiece312 through power cable 342. CPU 316 may also use data supplied bysensor 322 to vary the operation of pump 318 through cable 344, whichaspirates fluid from handpiece 312 through line 346 and into collectioncontainer 328 through line 348. CPU 316 may also use data supplied bysensor 322 and the applied output of power supply 320 to provide audibletones to the user.

As seen in FIG. 5, in a fifth embodiment of the present invention,control system 410 for use in operating handpiece 412 includes controlconsole 414. Control console 414 generally includes control module orCPU 416, aspiration pump 418, handpiece power supply 420, valve 424,pressurizing source 429, and pressure sensor 427. Airflow sensor 423 isconnected to pressurizing source 429 and infusion source 426 throughlines 432 and 452. Sensor 423 may be any commercially available flowsensor, such as Model AWM3100V available from Honeywell Micro Switch,Freeport, Ill. Infusion source 426 may be any commercially availableirrigation solution provided in bottles.

In use, sensor 423 measures the flow of air into the infusion source 426and supplies this information to CPU 416 through cable 436. The airflowdata may be used by CPU 416 along with information from pressure sensor427 for the calculation of infusion flow to the handpiece through line434. This infusion flow calculation may be used to control the operatingparameters of console 414 using software commands that are well known inthe art. For example, CPU 416, through cable 450, may controlpressurizing source 429 while reading pressure sensor 427 data throughcable 456 so as to vary the pressure and amount of irrigation fluidreaching handpiece 412 from source 426. CPU 416 may also, through cable440, vary the output of power supply 420 being sent to handpiece 412through power cable 442. CPU 416 may also use this infusion flowcalculation to vary the operation of pump 418 through cable 444, whichaspirates fluid from handpiece 412 through line 446 and into collectioncontainer 428 through line 448. CPU 416 may also use this infusion flowcalculation and the applied output of power supply 420 to provideaudible tones to the user.

As seen in FIG. 6, in a sixth embodiment of the present invention,control system 510 for use in operating handpiece 512 includes controlconsole 514. Control console 514 generally includes control module orCPU 516, aspiration pump 518, handpiece power supply 520, valve 524,pressurizing source 530, and pressure sensor 527. Infusion source 525may be any commercially available irrigation solution provided in bagsor a custom compliant container. Pressurizing source 530 is acompressing device that squeezes infusion source 525 through mechanicallink 553 in order to pressurize the fluid. The rate of compression ofthe infusion source is controlled by CPU 516 through cable 550.

In use, CPU 516 calculates the infusion flow to the handpiece throughline 534 based on the compression rate of pressurizing source 530 andthe pressure data from pressure sensor 527. This infusion flowcalculation may be used to control the operating parameters of console514 using software commands that are well known in the art. For example,CPU 516, through cable 550, may control pressurizing source 530 whilereading pressure sensor 527 data through cable 556 so as to vary thepressure and amount of irrigation fluid reaching handpiece 512 fromsource 525. CPU 516 may also, through cable 540, vary the output ofpower supply 520 being sent to handpiece 512 though power cable 542. CPU516 may also use this infusion flow calculation to vary the operation ofpump 518 through cable 544, which aspirates fluid from handpiece 512through line 546 and into collection container 528 through line 548. CPU516 may also use this infusion flow calculation and the applied outputof power supply 520 to provide audible tones to the user.

As seen in FIG. 7, when the system of the present invention ismonitoring infusion flow, the system monitors the current infusion flowand compares the actual flow against a predetermined flow rate. Ifinfusion flow is above the predetermined rate, no action is taken by thesystem. If the infusion flow is below the predetermined rate, the systemmay take a variety of actions, such as changing the power delivered tothe ultrasound handpiece, providing a variable tone to the surgeon orchanging the aspiration pressure.

This description is given for purposes of illustration and explanation.It will be apparent to those skilled in the relevant art that changesand modifications may be made to the invention described above withoutdeparting from its scope or spirit.

We claim:
 1. A method of controlling the operating parameters of asurgical system, the method comprising the steps of: a) providing asurgical system having, i) an aspiration pump, ii) a control modulecapable of varying the operation of the aspiration pump and iii) aninfusion fluid flow sensor capable of providing infusion fluid flowinformation to the control module; b) setting a predetermined infusionfluid flow rate in the control module; c) measuring a current actualinfusion fluid flow rate with the infusion fluid flow sensor andproviding the current infusion fluid flow rate to the control module; d)comparing the current actual infusion fluid flow rate with thepredetermined infusion fluid flow rate in the control module; and e)varying the operation of the aspiration pump if the current actualinfusion fluid flow rate is below the predetermined infusion fluid flowrate.
 2. A method of controlling the operating parameters of a surgicalsystem, the method comprising the steps of: a) providing a surgicalsystem having, i) an ultrasound handpiece, ii) a control module capableof varying the operation of the ultrasound handpiece and iii) aninfusion fluid flow sensor capable of providing infusion fluid flowinformation to the control module; b) setting a predetermined infusionfluid flow rate in the control module; c) measuring a current actualinfusion fluid flow rate with the infusion fluid flow sensor andproviding the current infusion fluid flow rate to the control module; d)comparing the current actual infusion fluid flow rate with thepredetermined infusion fluid flow rate in the control module; and e)varying the operation of the ultrasound handpiece if the current actualinfusion fluid flow rate is below the predetermined infusion fluid flowrate.
 3. A method of controlling the operating parameters of a surgicalsystem, the method comprising the steps of: a) providing a surgicalsystem having, i) a control module capable of producing audible tonesand ii) an infusion fluid flow sensor capable of providing infusionfluid flow information to the control module; b) setting a predeterminedinfusion fluid flow rate in the control module; c) measuring a currentactual infusion fluid flow rate with the infusion fluid flow sensor andproviding the current infusion fluid flow rate to the control module; d)comparing the current actual infusion fluid flow rate with thepredetermined infusion fluid flow rate in the control module; and e)providing an audible tone if the current actual infusion fluid flow rateis below the predetermined infusion fluid flow rate.
 4. A method ofcontrolling the operating parameters of a surgical system, the methodcomprising the steps of: a) providing a surgical system having, i) aninfusion fluid source, ii) a source for pressurizing the infusion fluidsource, iii) a control module capable of varying the operation of thesource for pressurizing the infusion fluid source and iv) an infusionfluid flow sensor capable of providing infusion fluid flow informationto the control module; b) setting a predetermined infusion fluid flowrate in the control module; c) measuring a current actual infusion fluidrate with the infusion fluid flow sensor and providing the currentinfusion fluid flow rate to the control module; d) comparing the currentactual infusion fluid flow rate with the predetermined infusion fluidflow rate in the control module; and e) varying the operation of thesource for pressurizing the infusion fluid source if the current actualinfusion fluid flow rate is below the predetermined infusion fluid flowrate.